Conventional text messaging systems typically involve creation of a text message on a mobile telephone having an alphanumeric keypad with a number of input keys and a display screen. A user wishing to send a text message will press appropriate input keys on the keypad in order to open up a window in which the text message can be created. The user enters text characters for the text message by pressing further keys on the keypad each having one or more associated letters of the alphabet and/or other text symbols. The entered text characters are displayed on the display screen of the mobile telephone for visual review by the user.
In multi-tap text entry systems, each input key has more than one associated text character or symbol, so a user must cycle through each of the available characters for a key by repeatedly pressing the key. For example, a single press of the ‘5’ key may cause a ‘j’ to be displayed on the screen, whereas two presses of the ‘5’ key may cause a ‘k’ to be displayed, and three presses of the ‘5’ key may cause an ‘1’ to be displayed. If a user is familiar with the text characters associated with each key, the user can create a text message by pressing on the keypad without looking at the electronic equipment display, so multi-tap systems can be used with little visual feedback from the user. However, multi-tap systems potentially require several keystrokes to enter a single letter so can lead to longer text message creation times.
In predictive text entry systems, each input key also has more than one associated text character or symbol, but instead of multiple key presses being required to enter a single character or symbol, more commonly used words may be entered using a single key press by the user. Predictive text systems will tend to reduce the number of key presses required to enter a word, as long as the word is included in the predictive text dictionary being used by the mobile telephone. A user presses the keys associated with each letter of the word they wish to type and as long as the predictive text dictionary contains the word in question and the key presses allow disambiguation of the word from other words in the dictionary, the word will be displayed on the screen. As one example, the sequence of key presses ‘93272’ may cause the word ‘zebra’ to be displayed on a screen. As another example, the sequence of key presses ‘2253’ may cause the word ‘able’ to be displayed on a screen, although several other words are possible (including cake, calf, bald, bake, etc.), so a user may be prompted for further input in order to disambiguate between each of the possible words. Well known predictive text systems include T9, provided by NUANCE COMMUNICATIONS and ITAP provided by MOTOROLA.
The T9 text prediction system includes a reduced keyboard disambiguating computer. The keyboard has twelve keys, nine of them labeled with numerous letters and other symbols, and those nine plus one more are labeled each with one of the ten digits. Textual entry keystrokes are ambiguous. The user strikes a delimiting “select” key at the end of each word, delimiting a keystroke sequence which could match any of many words with the same number of letters. The keystroke sequence is processed with a complete dictionary, and words which match the sequence of keystrokes are presented to the user in order of decreasing frequency of use. The user selects the desired word. The letters are assigned to the keys in a non-sequential order which reduces chances of ambiguities. The same “select” key is pressed to select the desired word, and spacing between words and punctuation is automatically computed. For words which are not in the dictionary, two keystrokes are entered to specify each letter. The system simultaneously interprets all keystroke sequences as both one stroke per letter and as two strokes per letter. The user selects the desired interpretation. The system also presents to the user the number which is represented by the sequence of keystrokes for possible selection by the user.
An on-line predictive text dictionary for use with electronic equipment in the form of a cellular radio telephone is also known.
Text messaging services are not widely available for analogue telephones because such telephones do not have any visual display capability by which a user may review the contents of a text message they are creating. Further, text prediction functionality is not available with such analogue telephones because such telephones do not have sufficient suitable data processing or data storage capabilities.
It would therefore be desirable to provide text messaging services including text prediction functionality to users of analogue telephones.